As the Internet has been widely used and the digital video and music contents have been used in recent years, more and more apparatuses with network capability have appeared, including not only information terminals such as personal computers, but also various household electrical appliances. When connecting information terminals such as personal computers for office use, a wired connection using an Ethernet (registered trademark) cable is mainly used. On the other hand, when connecting household electrical appliances or connecting a household electrical appliance and another information terminal, a wireless connection is required in consideration of the flexibility in arrangement, and restrictions on the size of small apparatuses such as digital still cameras. However, in a wireless connection, the transmission performance may significantly degrade or change due to a state of the radio propagation environment or a change in the state. As means for reducing the influence of such a change in the state of the radio propagation environment, there is a method of controlling the directional patterns of transmitting and receiving antennas provided on an information terminal or a household electrical appliance, according to the radio propagation environment.
In an antenna steering control system disclosed in Patent Literature 1, a transmitting apparatus transmits a measurement signal to a receiving apparatus, for determining a radio propagation delay time. Upon receiving the measurement signal, the receiving apparatus controls its antenna control means to change the beam width of each antenna element in a steerable receiving antenna of the receiving apparatus to be the widest. The receiving apparatus continues to receive the measurement signal with the beam widths being widest, separates the measurement signal into a direct wave and delay waves, and computes the delay spread. Based on the computation result, the receiving apparatus controls the directional pattern of the steerable antenna to an optimum pattern.